Yieldable carrier for motion-transmitting devices



W. R. UGGLA Nov.'11, 1930.

YIELDABLE CARRIER FOR MOTION TRANSMITTING DEVICES Original Filed Sept. 4, 1928 Patented Nov. 11, 1930 (UNITED s'rA'rss PATENT OFFICE WILHELM ROBERT UGGLA, OF MORBY, STOOKSUND, SWEDEN, ASSIGNOR 'IO LUTH &

nosmvn ELEKTRISKA SWEDEN AK'IIEBOLAG, OF STOOKHOLLI, SWEDEN, A CORPORATION OF YIELDABLE CARRIER FOR MOTION-TRANSMITTING- DEVICES Application flled September 4, 1928, 'Serial No.

The present invention relates to power transmission. More particularly, it relates to tated at slow speeds. Still more particularly,

power transmission by means of speed-reducing gearing for the purpose of driving extremely heavy apparatus adapted to be rothe invention relates to cement mill drives using speed reducing gear transmission, although the invention is not limited solely to such application, but may be applied in drives for operating rolling mills, sugar mills and the like.

The bearings supporting the great weight of cement and like mills are subject to considerable wear and in the case of cement mills particularly, where'alignment of the mill is not essential, it is desirable to be able to per- Y mit the mill'to operate after more play has impractical, however, since the large amount of power required, coupled with the slow speed of rotation of the mill, requires the transmission of greater turning forces at the mill shaft than can be transmitted through known forms of flexible couplings without undue wear and frequent failure thereof.

The purpose of the present invention is to overcome the heretofore encountered diificulties in mill drives of the above character by providing a novel form of drive in which the mill is rigidly coupled to a power-transmitting unit and in which said unit is not subjected to excessive or destructive stresses upon wear or even complete failure of the mill bearings. The manner in which the above purpose is achieved may best be understood from the following description of a preferred embodiment of the invention, taken in conjunction 303,900, and Sweden May 21, 1926. Benewed March 27, 1930.

with the accompanying drawings forming part of this specification.

In the drawings:

Fig. 1 is a fragmentary side elevation showing part of a cement mill and the driving means therefor; and

Fig. 2 is an end elevation looking from the right of Fig. 1, the mill being omitted.

The cement mill 1, of the ordinary known form, comprises a rotary barrel 2 terminating at one end in a shaft 3 journalled in hearing 4. Bearing 4 is supported upon the foundation 5. The opposite end of mill 1 is supported by a second bearing, not shown.

Shaft 3 may be driven, through a speed-reducing gear transmission 6, by any suitable form of prime mover, but is preferably driven by an electric motor 7 having a driving shaft earings than co ld b m1. 8 operating at relatively high speed.

The transmission 6 comprises a high speed power input shaft 9 and a low speed power output shaft 10.

These shafts are journalled in a rigid casing 11 forming part of the transmission and are connected by gearing the specific form and arrangement of which does not form a part of the present invention and which has there fore not been shown.

The low speed shafts 3 and 10 are connected by the ri id coupling 12, said coupling being referab y formed by flanged members rigidy secured to the shafts and bolted to each other by bolts 13.

The high speed shafts 8 and 9 may be connected by means of a' flexible coupling of any suitable form. In the embodiment shown the flexible coupling consists of pairs of flat springs 14 and 15 fixed on arms 16 and 17 respectively on the shafts 8 and 9. The adjacent ends of springs 14 and 15 are secured to the peripheries of spring discs 18 and 19 respectively, these discs being in turn fixedly connected at their centers.

It will be evident that this construction not only permits shafts 8 and 9 to operate when their axes are at an angle to each other, but also permits their operation when axially oflsetfrom each other. Further, it will be evident that since the flexible coupling transmits the required power at relatively high speed, relatively low as compared with the torsional stress on the low speed coupling 12. Because of the-relatively low stresses imposed, a flexible coupling can be used satisfactorily between the motor and the transmission.

The motor 7 is fixedly supported by a part of foundation 5, but the. transmission 6 is resiliently supported by means of a plurality of coil springs 20 mounted on pedestals 21 and engaging the casing 11. As will be seen from Fig. 2, springs 20 and pedestals 21 are laterally offset from the axis of rotation of the lined driving and driven shafts of the mechanism. The sole support of the transmission is formed by springs 20.

From the foregoing description it will be seen that the resiliently supported transmission, instead of having to bear any of the weight of the-mill when bearing 4 wears, 1S able to follow the downward movement of shaft 3 as the bearing wears, by compressing springs 2. In this connection the strength of the springs 20 employed is of major importance, as may best be illustrated by a concrete example.

Let it be assumed that the mill requires 300 horsepower for its operation, turns at 20 revolutions per minute, and is driven by a motor operating at 1,000 revolutions per minute. A 50 to 1 reduction gear transmission for delivering 300 horse-power at 20 revolutions per minute will weigh about 20,000 pounds, and for such a transmission the springs 20 should be of such strength that they are compressed about eight inches due to the weight of the transmission. If, now, bearing 4 wears so that shaft 3 and the rigidly connected transmission are lowered by as much as three-eights of an inch, the total compression of the springs will then be only eight and three-eighths inches, and

the upward tin 11st of the springs in excess of that balanced by the weight of the transmission will amount to but little over 900 pounds. This excess thrust will be imposed on the bearings and journals of the transmission, but since they are designed to take the weight of the entire gearing, weighin many times this amount, the increased loa on these hearings is negligible from an operating standpoint. So also is the bending stress imposed on shaft 3 due to the unbalanced upward thrust of the springs.

Springs 20 also should be located so that they are all under compression when the mill is in operation under load, as well as when it isat rest. To this end they should be ofiset from the central axis of rotation as far as conveniently possible, in order to increase the moment arm through which they act in resisting reaction turning moments caused by power load on the transmission.

The factors of weight, power, spring .the torsional stress thereon is strength, etc., will vary widely with individual installations, but in order to derive the full benefit of the invention,.'the springs 20 should be of such strength that the compression thereof due to the weight of the trans mission is materially greater than the further compression which may be imposed thereon due to permissible wear in the mill bearings. V

It will be evident that the springs also serve as shock absorbing bufl'ers permitting a certain resilience in the drive which may prevent damage to the driving. mechanism by absorbing shocks. This is particularly true in cases where the load on the mill varies.

- Further, the action of the springs may be controlled by dash-pots, such dash-pots conveniently comprising pistons connected to the transmission casing and operating in air or oil filled chambers.

While for illustrative purposes I have shown a preferred embodiment of the inven-' tion, the invention is to be understood as embracing all such changes andmodifications as may fall within the scope of the appended claims. I

What I claim is:

1. A prime mover, apparatus to be driven thereby, a power transmitting gear transmission for transmitting drive from said prime mover to said apparatus, means for resiliently supporting the entire transmission with respect to the driven apparatus, and a rigid coupling between the transmission and the driven apparatus.

2.. A high-speed prime mover, a low-speed apparatus to be driven thereby, a speed-reducing gear transmission for transmitting drive from said prime mover to said-apparatus, means for resiliently supporting the en'- tire transmission with respect to sald apparatus, and a rigid coupling between the transmission and the driven apparatus.

3. A prime mover, apparatus to be driven I thereby, a gear transmisison for transmitting power from the prime mover to the apparatus, a rigid coupling between the transmission and the apparatus, a flexible coupling between the prime mover and the transmission, and resilient means for supporting the transmission.

4. A prime mover comprising a high-speed driving shaft, an apparatus to be driven thereby comprising a low-speed driven shaft, a speed-reducing gear transmission comprising a high-speed power input shaft, a lowthereby comprising a low-speed driven shaft, a speed-reducing gear transmission comprising a high-speed power input shaft, a lowspeed power output shaft and a rigid casing in which the transmission shafts are journalled, a rigid coupling between the driven shaft and the power output shaft, a flexible coupling between the driving shaft and the power input shaft, and a plurality of coil springs for resiliently supporting said casmg.

6. In combination, a cement mill, a prime mover, a gear transmission for transmitting drive from the prime mover to the mill, means for resiliently supporting the entire transmission with respect to the mill, and a rigid conlpling between the transmission and the m1 7. In combination, a cement mill, a highspeed prime mover, a speed-reducing gear transmission for transmitting drive from the prime mover to the mill, a rigid coupling between the mill and the transmission, a flexible coupling between the transmission and the prime mover, and a plurality of springs for resiliently supporting said transmission.

8. In combination, a mill comprising a lowspeed driven shaft, a prime mover comprising a high-speed driving shaft, a speed-reducing gear transmision comprising a highspeed power input shaft, a low-speed power output shaft in axial alignment with the input shaft, and a rigid casing in which the transmission shafts are journalled, a rigid coupling between the power output shaft and the driven shaft, a flexible coupling between the power input shaft and the driving shaft, and a plurality of springs for resiliently supporting said casing at points laterally offset from the axis of the aligned shafts.

9. In combination, a mill comprising a low-speed driven shaft, a prime mover comprising a high-speed driving shaft, a speedreducing gear transmission comprising a high-speed power input shaft, a low-speed power output shaft in axial alignment with the input shaft and a rigid casing in which the transmision shafts are journaled, a rigid coupling between the power output shaft and the driven shaft, a flexible coupling between the power input shaft and the driving shaft, and laterally spaced rows of coil springs for resiliently supporting said casing on opposite sides thereof.

10. In combination, a mill, a high-speed prime mover, a speed-reducing gear transmission for transmitting drive from the prime mover to the mill, a rigid coupling between the mill and the prime mover, a flexible coupling between the transmission and the prime mover, and a plurality of springs for resiliently supporting said transmission on opposite sides thereof, the positioning of said springs and the weight of the transmission being so related to the reaction forces developed in the transmission when it is under power load that all of the springs bear some 0 the weight of the transmission at all times.

11. In combination, an apparatus comprising a driven shaft, a bearing for said shaft, a power transmission comprising a casing and a power output shaft journaled therein, a rigid coupling between said shafts and springs for resiliently supporting said casing, said springs being arranged to be compressed due to the weight of the transmission and to be further compressed upon lowering of said shafts due to wear in said hearing and the strength of said springs being such that compression thereof the to the weight of the transmission is so great that the additional compression thereof due to maximum permissible wear in said bearing does not increase the bearing pressure on said power output shaft beyond permissible limits.

12. In combination, an apparatus comprising a driven shaft, a bearing for said shaft, a power transmission comprising a casing and a power output shaft journaled therein, a rigid coupling between said shafts and springs for resiliently supporting said casing, said springs being arranged to be compressed due to the weight of the transmission and to be further compressed upon lowering of said shafts due to wear in said bearing, the length of said springs when loaded by said transmission alone being less than the unloaded length of the springs by an amount several times the additional distance of compression due to the maximum 'permissible wear in said bearing.

13. Yieldable carrying means for speed transformers constituting a separate unit, characterized by the casing of said transformer being supported by springs with such a great compression capacity that the casing is able to partake in variations in the position of the shaft of a machine driven by the transformer and connected to the same by means of a rigid coupling.

In testimony whereof I have hereunto affixed my signature. I

WILHELM ROBERT UGGLA. 

